NR PHR design for mmWave deployment

ABSTRACT

New radio (NR) power headroom report (PHR) design for millimeter wave (mmWave) deployment is discussed. The power control process for mmWave may include beam-specific periodic PHR reporting and user equipment (UE)-specific event-trigger PHR reporting. The periodic PHR reporting may either provide a single PHR that includes power headroom information for each of the serving beams, or the UE may be configured to measure and report PHR for different beams in different slots. When reporting a single PHR with power headroom information for multiple serving beams, a beam index may be included in the reserved bits of the PHR. For the event-trigger PHR, the PHR reported based on a detected event trigger may provide power headroom information only for the current serving beam, or for all serving beams.

This application claims the benefit of PCT/CN2017/084143, entitled, “NRPHR DESIGN FOR MMWAVE DEPLOYMENT” filed on May 12, 2017, which isexpressly incorporated by reference herein in its entirety.

BACKGROUND Field

Aspects of the present disclosure relate generally to wirelesscommunication systems, and more particularly, to new radio (NR) powerheadroom report (PHR) design for millimeter wave (mmWave) deployment.

Background

Wireless communication networks are widely deployed to provide variouscommunication services such as voice, video, packet data, messaging,broadcast, and the like. These wireless networks may be multiple-accessnetworks capable of supporting multiple users by sharing the availablenetwork resources. Such networks, which are usually multiple accessnetworks, support communications for multiple users by sharing theavailable network resources. One example of such a network is theUniversal Terrestrial Radio Access Network (UTRAN). The UTRAN is theradio access network (RAN) defined as a part of the Universal MobileTelecommunications System (UMTS), a third generation (3G) mobile phonetechnology supported by the 3rd Generation Partnership Project (3GPP).Examples of multiple-access network formats include Code DivisionMultiple Access (CDMA) networks, Time Division Multiple Access (TDMA)networks, Frequency Division Multiple Access (FDMA) networks. OrthogonalFDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.

A wireless communication network may include a number of base stationsor node Bs that can support communication for a number of userequipments (UEs). A UE may communicate with a base station via downlinkand uplink. The downlink (or forward link) refers to the communicationlink from the base station to the UE, and the uplink (or reverse link)refers to the communication link from the UE to the base station.

A base station may transmit data and control information on the downlinkto a UE and/or may receive data and control information on the uplinkfrom the UE. On the downlink, a transmission from the base station mayencounter interference due to transmissions from neighbor base stationsor from other wireless radio frequency (RF) transmitters. On the uplink,a transmission from the UE may encounter interference from uplinktransmissions of other UEs communicating with the neighbor base stationsor from other wireless RF transmitters. This interference may degradeperformance on both the downlink and uplink.

As the demand for mobile broadband access continues to increase, thepossibilities of interference and congested networks grows with more UEsaccessing the long-range wireless communication networks and moreshort-range wireless systems being deployed in communities. Research anddevelopment continue to advance wireless technologies not only to meetthe growing demand for mobile broadband access, but to advance andenhance the user experience with mobile communications.

SUMMARY

In one aspect of the disclosure, a method of wireless communicationincludes determining, by a UE, a beam-specific periodic power headroomreport (PHR) in response to expiration of a first reporting timer,wherein the UE receives communications from a serving base station overone or more serving beams beamformed by the serving base station,transmitting, by the UE, the beam-specific periodic PHR to the servingbase station, detecting, by the UE, a report triggering event,determining, by the UE, a UE-specific trigger PHR in response to thereport triggering event and expiration of a second reporting timer, andtransmitting, by the UE, the UE-specific trigger PHR to the serving basestation.

In an additional aspect of the disclosure, a method of wirelesscommunication includes receiving, at a UE, an identification signal froma serving base station, wherein the identification signal identifies oneor more reference signals for pathloss measurement, measuring, by theUE, a pathloss on the one or more reference signals identified by theidentification signal, comparing, by the UE, the pathloss to a thresholdtrigger value, and activating, by the UE, power headroom reporting inresponse to the pathloss exceeding the threshold trigger value.

In an additional aspect of the disclosure, a method of wirelesscommunication includes determining, by a UE, a time period since a lastbeam change of one or more serving beams received at the UE from aserving base station, measuring, by the UE, a pathloss of abeam-specific layer 3 reference signal on a current serving beam inresponse to the time period exceeding a minimum time threshold, andmeasuring, by the UE, the pathloss of a beam-specific layer 1 referencesignal on the current serving beam in response to the time period beingbelow the minimum time threshold.

In an additional aspect of the disclosure, an apparatus configured forwireless communication, includes means for determining, by a UE, abeam-specific periodic PHR in response to expiration of a firstreporting timer, wherein the UE receives communications from a servingbase station over one or more serving beams beamformed by the servingbase station, means for transmitting, by the UE, the beam-specificperiodic PHR to the serving base station, means for detecting, by theUE, a report triggering event, means for determining, by the UE, aUE-specific trigger PHR in response to the report triggering event andexpiration of a second reporting timer, and means for transmitting, bythe UE, the UE-specific trigger PHR to the serving base station.

In an additional aspect of the disclosure, an apparatus configured forwireless communication, includes means for receiving, at a UE, anidentification signal from a serving base station, wherein theidentification signal identifies one or more reference signals forpathloss measurement, means for measuring, by the UE, a pathloss on theone or more reference signals identified by the identification signal,means for comparing, by the UE, the pathloss to a threshold triggervalue, and means for activating, by the UE, power headroom reporting inresponse to the pathloss exceeding the threshold trigger value.

In an additional aspect of the disclosure, an apparatus configured forwireless communication, includes means for determining, by a UE, a timeperiod since a last beam change of one or more serving beams received atthe UE from a serving base station, means for measuring, by the UE, apathloss of a beam-specific layer 3 reference signal on a currentserving beam in response to the time period exceeding a minimum timethreshold, and means for measuring, by the UE, the pathloss of abeam-specific layer 1 reference signal on the current serving beam inresponse to the time period being below the minimum time threshold.

In an additional aspect of the disclosure, a non-transitorycomputer-readable medium having program code recorded thereon. Theprogram code further includes code to determine, by a UE, a beamspecific periodic PHR in response to expiration of a first reportingtimer, wherein the UE receives communications from a serving basestation over one or more serving beams beamformed by the serving basestation, code to transmit, by the UE, the beam-specific periodic PHR tothe serving base station, code to detect, by the UE, a report triggeringevent, code to determine, by the UE, a UE-specific trigger PHR inresponse to the report triggering event and expiration of a secondreporting timer, and code to transmit, by the UE, the UE-specifictrigger PHR to the serving base station.

In an additional aspect of the disclosure, a non-transitorycomputer-readable medium having program code recorded thereon. Theprogram code further includes code to receive, at a UE, anidentification signal from a serving base station, wherein theidentification signal identifies one or more reference signals forpathloss measurement, code to measure, by the UE, a pathloss on the oneor more reference signals identified by the identification signal, codeto compare, by the UE, the pathloss to a threshold trigger value, andcode to activate, by the UE, power headroom reporting in response to thepathloss exceeding the threshold trigger value.

In an additional aspect of the disclosure, a non-transitorycomputer-readable medium having program code recorded thereon. Theprogram code further includes code to determine, by a UE, a time periodsince a last beam change of one or more serving beams received at the UEfrom a serving base station, code to measure, by the UE, a pathloss of abeam-specific layer 3 reference signal on a current serving beam inresponse to the time period exceeding a minimum time threshold, and codeto measure, by the UE, the pathloss of a beam-specific layer 1 referencesignal on the current serving beam in response to the time period beingbelow the minimum time threshold.

In an additional aspect of the disclosure, an apparatus configured forwireless communication is disclosed. The apparatus includes at least oneprocessor, and a memory coupled to the processor. The processor isconfigured to determine, by a UE, a beam-specific periodic PHR inresponse to expiration of a first reporting timer, wherein the UEreceives communications from a serving base station over one or moreserving beams beamformed by the serving base station, to transmit, bythe UE, the beam-specific periodic PHR to the serving base station, todetect, by the UE, a report triggering event, to determine, by the UE, aUE-specific trigger PHR in response to the report triggering event andexpiration of a second reporting timer, and to transmit, by the UE, theUE-specific trigger PHR to the serving base station.

In an additional aspect of the disclosure, an apparatus configured forwireless communication is disclosed. The apparatus includes at least oneprocessor, and a memory coupled to the processor. The processor isconfigured to receive, at a UE, an identification signal from a servingbase station, wherein the identification signal identifies one or morereference signals for pathloss measurement, to measure, by the UE, apathloss on the one or more reference signals identified by theidentification signal, to compare, by the UE, the pathloss to athreshold trigger value, and to activate, by the UE, power headroomreporting in response to the pathloss exceeding the threshold triggervalue.

In an additional aspect of the disclosure, an apparatus configured forwireless communication is disclosed. The apparatus includes at least oneprocessor, and a memory coupled to the processor. The processor isconfigured to determine, by a UE, a time period since a last beam changeof one or more serving beams received at the UE from a serving basestation, to measure, by the UE, a pathloss of a beam-specific layer 3reference signal on a current serving beam in response to the timeperiod exceeding a minimum time threshold, and to measure, by the UE,the pathloss of a beam-specific layer 1 reference signal on the currentserving beam in response to the time period being below the minimum timethreshold.

The foregoing has outlined rather broadly the features and technicaladvantages of examples according to the disclosure in order that thedetailed description that follows may be better understood. Additionalfeatures and advantages will be described hereinafter. The conceptionand specific examples disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present disclosure. Such equivalent constructions do notdepart from the scope of the appended claims. Characteristics of theconcepts disclosed herein, both their organization and method ofoperation, together with associated advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. Each of the figures is provided for the purpose ofillustration and description, and not as a definition of the limits ofthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentdisclosure may be realized by reference to the following drawings. Inthe appended figures, similar components or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIG. 1 is a block diagram illustrating details of a wirelesscommunication system.

FIG. 2 is a block diagram illustrating a design of a base station and aUE configured according to one aspect of the present disclosure.

FIG. 3 is a block diagram illustrating a wireless communication systemincluding base stations that use directional wireless beams.

FIG. 4 is a block diagram illustrating example blocks executed toimplement one aspect of the present disclosure.

FIG. 5 is a block diagram illustrating a base station communicating witha UE using mmWave beamforming, in which the base station and UE areconfigured according to aspects of the present disclosure.

FIGS. 6A-6C are block diagrams illustrating a base station and UEconfigured according to aspects of the present disclosure.

FIG. 7 is a block diagram illustrating example blocks executed toimplement one aspect of the present disclosure.

FIG. 8 is a block diagram illustrating example blocks executed toimplement one aspect of the present disclosure.

FIG. 9 is a block diagram illustrating an configured according to oneaspect of the present disclosure.

The Appendix provides further details regarding various embodiments ofthis disclosure and the subject matter therein forms a part of thespecification of this application.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings and appendix, is intended as a description of variousconfigurations and is not intended to limit the scope of the disclosure.Rather, the detailed description includes specific details for thepurpose of providing a thorough understanding of the inventive subjectmatter. It will be apparent to those skilled in the art that thesespecific details are not required in every case and that, in someinstances, well-known structures and components are shown in blockdiagram form for clarity of presentation.

This disclosure relates generally to providing or participating inauthorized shared access between two or more wireless communicationssystems, also referred to as wireless communications networks. Invarious embodiments, the techniques and apparatus may be used forwireless communication networks such as code division multiple access(CDMA) networks, time division multiple access (TDMA) networks,frequency division multiple access (TDMA) networks, orthogonal FDMA(OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks,GSM networks, 5^(th) Generation (5G) or new radio (NR) networks, as wellas other communications networks. As described herein, the terms“networks” and “systems” may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA(E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and thelike. UTRA, E-UTRA, and Global System for Mobile Communications (GSM)are part of universal mobile telecommunication system (UMTS). Inparticular, long term evolution (LTE) is a release of UMTS that usesE-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documentsprovided from an organization named “3rd Generation Partnership Project”(3GPP), and cdma2000 is described in documents from an organizationnamed “3rd Generation Partnership Project 2” (3GPP2). These variousradio technologies and standards are known or are being developed. Forexample, the 3rd Generation Partnership Project (3GPP) is acollaboration between groups of telecommunications associations thataims to define a globally applicable third generation (3G) mobile phonespecification. 3GPP long term evolution (LTE) is a 3GPP project whichwas aimed at improving the universal mobile telecommunications system(UMTS) mobile phone standard. The 3GPP may define specifications for thenext generation of mobile networks, mobile systems, and mobile devices.The present disclosure is concerned with the evolution of wirelesstechnologies from LTE, 4G, 5G, NR, and beyond with shared access towireless spectrum between networks using a collection of new anddifferent radio access technologies or radio air interfaces.

In particular, 5G networks contemplate diverse deployments, diversespectrum, and diverse services and devices that may be implemented usingan OFDM-based unified, air interface. In order to achieve these goals,further enhancements to LTE and LTE-A are considered in addition todevelopment of the new radio technology for 5G NR networks. The 5G NRwill be capable of scaling to provide coverage (1) to a massive Internetof things (IoTs) with an ultra-high density (e.g., ˜1M nodes/km²),ultra-low complexity (e.g., ˜10 s of bits/sec), ultra-low energy (e.g.,˜10+ years of battery life), and deep coverage with the capability toreach challenging locations; (2) including mission-critical control withstrong security to safeguard sensitive personal, financial, orclassified information, ultra-high reliability (e.g., ˜99.9999%reliability), ultra-low latency (e.g., ˜1 ms), and users with wideranges of mobility or lack thereof; and (3) with enhanced mobilebroadband including extreme high capacity (e.g., ˜10 Tbps/km²), extremedata rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates),and deep awareness with advanced discovery and optimizations.

The 5G NR may be implemented to use optimized OFDM-based waveforms withscalable numerology and transmission time interval (TTI); having acommon, flexible framework to efficiently multiplex services andfeatures with a dynamic, low-latency time division duplex(TDD)/frequency division duplex (FDD) design; and with advanced wirelesstechnologies, such as massive multiple input, multiple output (MIMO),robust millimeter wave (mmWave) transmissions, advanced channel coding,and device-centric mobility. Scalability of the numerology in 5G NR,with scaling of subcarrier spacing, may efficiently address operatingdiverse services across diverse spectrum and diverse deployments. Forexample, in various outdoor and macro coverage deployments of less than3 GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz,for example over 1, 5, 10, 20 MHz, and the like bandwidth. For othervarious outdoor and small cell coverage deployments of TDD greater than3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHzbandwidth. For other various indoor wideband implementations, using aTDD over the unlicensed portion of the 5 GHz band, the subcarrierspacing may occur with 60 kHz over a 160 MHz bandwidth. Finally, forvarious deployments transmitting with mmWave components at a TDD of 28GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz bandwidth.

The scalable numerology of the 5G NR facilitates scalable TTI fordiverse latency and quality of service (QoS) requirements. For example,shorter TTI may be used for low latency and high reliability, whilelonger TTI may be used for higher spectral efficiency. The efficientmultiplexing of long and short TTIs to allow transmissions to start onsymbol boundaries. 5G NR also contemplates a self-contained integratedsubframe design with uplink/downlink scheduling information, data, andacknowledgement in the same subframe. The self-contained integratedsubframe supports communications in unlicensed or contention-basedshared spectrum, adaptive uplink/downlink that may be flexiblyconfigured on a per-cell basis to dynamically switch between uplink anddownlink to meet the current traffic needs.

Various other aspects and features of the disclosure are furtherdescribed below. It should be apparent that the teachings herein may beembodied in a wide variety of forms and that any specific structure,function, or both being disclosed herein is merely representative andnot limiting. Based on the teachings herein one of an ordinary level ofskill in the art should appreciate that an aspect disclosed herein maybe implemented independently of any other aspects and that two or moreof these aspects may be combined in various ways. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, such an apparatusmay be implemented or such a method may be practiced using otherstructure, functionality, or structure and functionality in addition toor other than one or more of the aspects set forth herein. For example,a method may be implemented as part of a system, device, apparatus,and/or as instructions stored on a computer readable medium forexecution on a processor or computer. Furthermore, an aspect maycomprise at least one element of a claim.

FIG. 1 is a block diagram illustrating 5G network 100 including variousbase stations and UEs configured according to aspects of the presentdisclosure. The 5G network 100 includes a number of base stations 105and other network entities. A base station may be a station thatcommunicates with the UEs and may also be referred to as an evolved nodeB (eNB), a next generation eNB (gNB), an access point, and the like.Each base station 105 may provide communication coverage for aparticular geographic area. In 3GPP, the term “cell” can refer to thisparticular geographic coverage area of a base station and/or a basestation subsystem serving the coverage area, depending on the context inwhich the term is used.

A base station may provide communication coverage for a macro cell or asmall cell, such as a pico cell or a femto cell, and/or other types ofcell. A macro cell generally covers a relatively large geographic area(e.g., several kilometers in radius) and may allow unrestricted accessby UEs with service subscriptions with the network provider. A smallcell, such as a pico cell, would generally cover a relatively smallergeographic area and may allow unrestricted access by UEs with servicesubscriptions with the network provider. A small cell, such as a femtocell, would also generally cover a relatively small geographic area(e.g., a home) and, in addition to unrestricted access, may also providerestricted access by UEs having an association with the femto cell(e.g., UEs in a closed subscriber group (CSG), UEs for users in thehome, and the like). A base station for a macro cell may be referred toas a macro base station. A base station for a small cell may be referredto as a small cell base station, a pico base station, a femto basestation or a home base station. In the example shown in FIG. 1, the basestations 105 d and 105 e are regular macro base stations, while basestations 105 a-105 c are macro base stations enabled with one of 3dimension (3D), full dimension (FD), or massive MIMO. Base stations 105a-105 c take advantage of their higher dimension MIMO capabilities toexploit 3D beamforming in both elevation and azimuth beamforming toincrease coverage and capacity. Base station 105 f is a small cell basestation which may be a home node or portable access point. A basestation may support one or multiple (e.g., two, three, four, and thelike) cells.

The 5G network 100 may support synchronous or asynchronous operation.For synchronous operation, the base stations may have similar frametiming, and transmissions from different base stations may beapproximately aligned in time. For asynchronous operation, the basestations may have different frame timing, and transmissions fromdifferent base stations may not be aligned in time.

The UEs 115 are dispersed throughout the wireless network 100, and eachUE may be stationary or mobile. A UE may also be referred to as aterminal, a mobile station, a subscriber unit, a station, or the like. AUE may be a cellular phone, a personal digital assistant (PDA), awireless modem, a wireless communication device, a handheld device, atablet computer, a laptop computer, a cordless phone, a wireless localloop (WLL) station, or the like. In one aspect, a UE may be a devicethat includes a Universal Integrated Circuit Card (UICC). In anotheraspect, a UE may be a device that does not include a UICC. In someaspects, UEs that do not include UICCs may also be referred to asinternet of everything (IoE) devices. UEs 115 a-115 d are examples ofmobile smart phone-type devices accessing 5G network 100 A UE may alsobe a machine specifically configured for connected communication,including machine type communication (MTC), enhanced MTC (eMTC),narrowband IoT (NB-IoT) and the like. UEs 115 e-115 k are examples ofvarious machines configured for communication that access 5G network100. A UE may be able to communicate with any type of the base stations,whether macro base station, small cell, or the like. In FIG. 1, alightning bolt (e.g., communication links) indicates wirelesstransmissions between a UE and a serving base station, which is a basestation designated to serve the UE on the downlink and/or uplink, ordesired transmission between base stations, and backhaul transmissionsbetween base stations.

In operation at 5G network 100, base stations 105 a-105 c serve UEs 115a and 115 b using 3D beamforming and coordinated spatial techniques,such as coordinated multipoint (CoMP) or multi-connectivity. Macro basestation 105 d performs backhaul communications with base stations 105a-105 c, as well as small cell, base station 105 f. Macro base station105 d also transmits multicast services which are subscribed to andreceived by UEs 115 c and 115 d. Such multicast services may includemobile television or stream video, or may include other services forproviding community information, such as weather emergencies or alerts,such as Amber alerts or gray alerts.

5G network 100 also support mission critical communications withultra-reliable and redundant links for mission critical devices, such UE115 e, which is a drone. Redundant communication links with UE 115 einclude from macro base stations 105 d and 105 e, as well as small cellbase station 105 f. Other machine type devices, such as UE 115 f(thermometer), UE 115 g (smart meter), and UE 115 h (wearable device)may communicate through 5G network 100 either directly with basestations, such as small cell base station 105 f, and macro base station105 e, or in multi-hop configurations by communicating with another userdevice which relays its information to the network, such as UE 115 fcommunicating temperature measurement information to the smart meter, UE115 g, which is then reported to the network through small cell basestation 105 f. 5G network 100 may also provide additional networkefficiency through dynamic, low-latency TDD/FDD communications, such asin a vehicle-to-vehicle (V2V) mesh network between UEs 115 i-115 kcommunicating with macro base station 105 e.

FIG. 2 shows a block diagram of a design of a base station 105 and a UE115, which may be one of the base station and one of the UEs in FIG. 1.At the base station 105, a transmit processor 220 may receive data froma data source 212 and control information from a controller/processor240. The control information may be for the PBCH, PCFICH, PHICH, PDCCH,EPDCCH, MPDCCH etc. The data may be for the PDSCH, etc. The transmitprocessor 220 may process (e.g., encode and symbol map) the data andcontrol information to obtain data. symbols and control symbols,respectively. The transmit processor 220 may also generate referencesymbols, e.g., for the primary synchronization signal (PSS), secondarysynchronization signal (SSS), and cell-specific reference signal. Atransmit (TX) multiple-input multiple-output (MIMO) processor 230 mayperform spatial processing (e.g., precoding) on the data symbols, thecontrol symbols, and/or the reference symbols, if applicable, and mayprovide output symbol streams to the modulators (MODs) 232 a through 232t. Each modulator 232 may process a respective output symbol stream(e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator232 may further process (e.g., convert to analog, amplify, filter, andupconvert) the output sample stream to obtain a downlink signal.Downlink signals from modulators 232 a through 232 t may be transmittedvia the antennas 234 a through 234 t, respectively.

At the UE 115, the antennas 252 a through 252 r may receive the downlinksignals from the base station 105 and may provide received signals tothe demodulators (DEMODs) 254 a through 254 r, respectively. Eachdemodulator 254 may condition (e.g., filter, amplify, downconvert, anddigitize) a respective received signal to obtain input samples. Eachdemodulator 254 may further process the input samples (e.g., for OFDM,etc.) to obtain received symbols. A MIMO detector 256 may obtainreceived symbols from all the demodulators 254 a through 254 r, performMIMO detection on the received symbols if applicable, and providedetected symbols. A receive processor 258 may process (e.g., demodulate,deinterleave, and decode) the detected symbols, provide decoded data forthe UE 115 to a data sink 260, and provide decoded control informationto a controller/processor 280.

On the uplink, at the UE 115, a transmit processor 264 may receive andprocess data (e.g., for the PUSCH) from a data source 262 and controlinformation (e.g., for the PUCCH) from the controller/processor 280. Thetransmit processor 264 may also generate reference symbols for areference signal. The symbols from the transmit processor 264 may beprecoded by a TX MIMO processor 266 if applicable, further processed bythe modulators 254 a through 254 r (e.g., for SC-FDM, etc.), andtransmitted to the base station 105. At the base station 105, the uplinksignals from the UE 115 may be received by the antennas 234, processedby the demodulators 232, detected by a MIMO detector 236 if applicable,and further processed by a receive processor 238 to obtain decoded dataand control information sent by the UE 115. The processor 238 mayprovide the decoded data to a data sink 239 and the decoded controlinformation to the controller/processor 240.

The controllers/processors 240 and 280 may direct the operation at thebase station 105 and the UE 115, respectively. The controller/processor240 and/or other processors and modules at the base station 105 mayperform or direct the execution of various processes for the techniquesdescribed herein. The controllers/processor 280 and/or other processorsand modules at the UE 115 may also perform or direct the execution ofthe functional blocks illustrated in FIGS. 4, 7, and 8, and/or otherprocesses for the techniques described herein. The memories 242 and 282may store data and program codes for the base station 105 and the UE115, respectively. A scheduler 244 may schedule UEs for datatransmission on the downlink and/or uplink.

Wireless communications systems operated by different network operatingentities (e.g., network operators) may share spectrum. In someinstances, a network operating entity may be configured to use anentirety of a designated shared spectrum for at least a period of timebefore another network operating entity uses the entirety of thedesignated shared spectrum for a different period of time. Thus, inorder to allow network operating entities use of the full designatedshared spectrum, and in order to mitigate interfering communicationsbetween the different network operating entities, certain resources(e.g., time) may be partitioned and allocated to the different networkoperating entities for certain types of communication.

For example, a network operating entity may be allocated certain timeresources reserved for exclusive communication by the network operatingentity using the entirety of the shared spectrum. The network operatingentity may also be allocated other time resources where the entity isgiven priority over other network operating entities to communicateusing the shared spectrum. These time resources, prioritized for use bythe network operating entity, may be utilized by other network operatingentities on an opportunistic basis if the prioritized network operatingentity does not utilize the resources. Additional time resources may beallocated for any network operator to use on an opportunistic basis.

Access to the shared spectrum and the arbitration of time resourcesamong different network operating entities may be centrally controlledby a separate entity, autonomously determined by a predefinedarbitration scheme, or dynamically determined based on interactionsbetween wireless nodes of the network operators.

In some cases, UE 115 and base station 105 may operate in a shared radiofrequency spectrum band, which may include licensed or unlicensed (e.g.,contention-based) frequency spectrum. In an unlicensed frequency portionof the shared radio frequency spectrum band, UEs 115 or base stations105 may traditionally perform a medium-sensing procedure to contend foraccess to the frequency spectrum. For example, UE 115 or base station105 may perform a listen before talk (LBT) procedure such as a clearchannel assessment (CCA) prior to communicating in order to determinewhether the shared channel is available. A CCA may include an energydetection procedure to determine whether there are any other activetransmissions. For example, a device may infer that a change in areceived signal strength indicator (RSSI) of a power meter indicatesthat a channel is occupied. Specifically, signal power that isconcentrated in a certain bandwidth and exceeds a predetermined noisefloor may indicate another wireless transmitter. A CCA also may includedetection of specific sequences that indicate use of the channel. Forexample, another device may transmit a specific preamble prior totransmitting a data sequence. In some cases, an LBT procedure mayinclude a wireless node adjusting its own backoff window based on theamount of energy detected on a channel and/or theacknowledge/negative-acknowledge (ACK/NACK) feedback for its owntransmitted packets as a proxy for collisions.

Use of a medium-sensing procedure to contend for access to an unlicensedshared spectrum may result in communication inefficiencies. This may beparticularly evident when multiple network operating entities (e.g.,network operators) are attempting to access a shared resource. In 5Gnetwork 100, base stations 105 and UEs 115 may be operated by the sameor different network operating entities. In some examples, an individualbase station 105 or UE 115 may be operated by more than one networkoperating entity. In other examples, each base station 105 and UE 115may be operated by a single network operating entity. Requiring eachbase station 105 and UE 115 of different network operating entities tocontend for shared resources may result in increased signaling overheadand communication latency.

FIG. 3 is a block diagram illustrating a wireless communication system300 including base stations that use directional wireless beams. Thewireless communication system 300 may be an example of the wirelesscommunication system 100 discussed with reference to FIG. 1. Thewireless communication system 300 includes a serving base station 305and a target base station 310. Coverage areas 315, 320 may be definedfor their respective base stations 305, 310. The serving base station305 and the target base station 310 may be examples of the base stations105 described with reference to FIG. 1. As such, features of the basestations 305, 310 may be similar to those of the base stations 105.

The serving base station 305 and the target base station 310 maycommunicate via a backhaul link 325. The backhaul link 325 may be awired backhaul link or a wireless backhaul link. The backhaul link 325may be configured to communicate data and other information between theserving base station 305 and the target base station 310. The backhaullink 325 may be an example of the backhaul links 134 described inreference to FIG. 1.

The serving base station 305 may establish a communication link 330 witha UE 115. The communication link 330 may be an example of thecommunication links 125 described with reference to FIG. 1. Onecharacteristic of UEs 115 in a wireless communication system 300 is thatthe UEs 115 may be mobile. Because UEs 115 may change their geophysicallocation in the wireless communication system 300, to maintainconnectivity, the UE 115 may desire to terminate its connection with theserving base station 305 and establish a new connection with a targetbase station 310. For example, as the UE 115 moves, the UE 115 mayapproach the limits of the coverage area 315 of the serving base station305. At the same time, however, the UE 115 may have passed within thecoverage area 320 of the target base station 310. In some examples, theUE 115 may determine a mobility parameter 335 of the UE 115. Themobility parameter 335 may indicate that the UE 115 is at a particularlocation, traveling in a particular direction, at a particular speed,other information related to the mobility of the UE 115, or anycombination thereof. When the UE 115 approaches the limits of thecoverage area 315 of the serving base station 305, a handover procedureof the UE 115 between the serving base station 305 and the target basestation 310 may be initiated.

In some examples of new radio (NR), the target base station 310 maycommunicate with UEs 115 via directional wireless communication links340 (sometimes 5 referred to as directional wireless beams ordirectional beams). The directional wireless communication links 340 maybe pointed in a specific direction and provide high-bandwidth linksbetween the target base station 310 and the UEs 115. Signal processingtechniques, such as beamforming, may be used to coherently combineenergy and thereby form the directional wireless communication links340. Wireless communication links achieved through beamforming may beassociated with narrow beams (e.g., “pencil beams”) that are highlydirectional minimize inter-link interference, and provide high-bandwidthlinks between wireless nodes (e.g., base stations, access nodes, UEsetc.). In some examples, the target base station 310 may operate inmillimeter wave (mmWave) frequency ranges, e.g., 28 GHz, 40 GHz, 60 GHz,etc. In some examples, the directional wireless communication links 340are transmitted using frequencies greater than 6 GHz. Wirelesscommunication at these frequencies may be associated with increasedsignal attenuation, e.g., path loss, which may be influenced by variousfactors, such as temperature, barometric pressure, diffraction, etc.Dynamic beam-steering and beam-search capabilities may further support,for example, discovery, link establishment, and beam refinement in thepresence of dynamic shadowing and Rayleigh fading. Additionally,communication in such mmWave systems may be time division multiplexed,where a transmission may only be directed to one wireless device at atime due to the directionality of the transmitted signal.

Each directional wireless communication link 340 may have a beam width345. The beam width 345 for each directional wireless communication link340 may be different (e.g., compare the beam width 345-a of thedirectional wireless communication link 340-a to the beam width 345-c ofthe directional wireless communication link 340-c). The beam width 345may related to the size of the phased array antenna used to generate thedirectional wireless communication link 340. Different beam widths 345may be used by the target base station 310 in different scenarios. Forexample, a first message may transmitted/received using a directionalwireless beam having a first beam width, while a second message may betransmitted/received using a directional wireless beam having a secondbeam width different than the first beam width. The target base station310 may generate any number of directional wireless communication links340 (e.g., directional wireless communication link 340-N). Thedirectional wireless communication links 340 generated by the targetbase station 310 may be pointed at any geographic location.

As a UE 115 moves in the wireless communication system 300, the UE 115may move out of the effective range of a particular directional wirelesscommunication link (see, e.g., directional wireless communication link340-a). Because of the narrow-beam width 345 of the directional wirelesscommunication links 340, the directional wireless communication links340 may provide coverage to a small geographic area. In contract, anomni-directional wireless communications link radiates energy in alldirections and covers a wide geographic area.

When a target base station 310 uses directional wireless communicationlinks 340 to establish a communication link with a UE 115, it mayfurther complicate a handover procedure. In some examples, the handoverprocedure discussed herein is a non-contention handover procedure.Control messages exchanged during a handover procedure may have latencybetween transmission and receipt. As such, there may be a delay of timebetween when a target base station 310 assigns resources to the UE 115and when the UE 115 may execute an operation using those assignedresources. In some examples, the handover procedure may have a latencythat spans a few tens to hundreds of milli-seconds. Due to UE mobility,rotation, or signal blockage, channel characteristics of a directionalwireless communication link 340 may change over time. In particular, thechannel characteristics of an assigned directional wirelesscommunication link 340 may change during the delays of the handoverprocedure. If a single resource (e.g., a single directional wirelesscommunication link 340) is assigned during a handover procedure, thehandover procedure may fail due to insufficient signal later in theprocess. Accordingly, handover procedures may be adjusted to account formultiple directional wireless beams that may be used to establish acommunication link between the target base station 310 and the UE 115during a handover procedure.

In LTE, the UE power headroom report (PHR) control element may be usedto report the power headroom available in the UE to a serving eNB. Thepower headroom of any given UE may be given by the following equation:P _(CMAX) =P _(MAX) −MPR−AMPR  (1)Where P_(CMAX) corresponds to the total maximum UE transmit power,P_(MAX) corresponds to the nominal UE maximum transmit power, MPRcorresponds to the maximum power reduction (MPR) value, and AMPRcorresponds to the additional MPR. In general, equation (1) identifiesthe difference between the nominal UE maximum transmit power and theestimated power for PUSCH transmission per activated serving cell. TheeNB may then use this information for efficient link adaptation andscheduling.

The current PHR format includes 8 bits octave, in which the powerheadroom may be encoded in 6 bits with a reporting range from −23 dB to+40 dB in steps of 1 dB, while the remaining 2 bits are reserved. PHRmay be transmitted at a subframe when the UE has uplink resourcesallocated for new transmissions. The PHR may be estimated over onesubframe with a reporting delay of 0 ms, resulting in power headroominformation being estimated and transmitted in the same subframe. Thenetwork may use this reported value to estimate how much uplinkbandwidth a UE can use for a specific subframe. In general, the moreresource blocks the UE is using, the higher the UE transmission powergets. However, the UE transmission power should not exceed the maximumtransmission power of the UE. Therefore, a given UE would not be able touse much resource block (bandwidth) for uplink transmissions if it doesnot have enough power headroom.

The PHR can be configured either for periodic reporting or eventthreshold reporting, such as when the downlink pathloss has changed by aspecific threshold amount. For periodic reporting, a report is triggeredat the expiration of the periodic PHR timer, which can be configuredwith various values (e.g., between 10 ms and infinity). For thresholdreporting, a PHR is triggered when the path loss changes by thepredefined threshold amount (1, 3, 6 or infinite dB), provided that asecond, configurable threshold reporting timer has also expired. Thethreshold reporting timer may start when a PHR has been transmitted andmay have various time values (e.g., between 0 and 1000 ms). Thethreshold reporting timer also prevents wasting of resources by sendingmultiple PHR when a UE is experiencing rapidly changing pathlossconditions.

As the periodic PHR timer gets shorter, the power headroom can be moreaccurate. However, the shorter periodic timer also causes the UE to sendmore frequent PHR, thus, expending more transmission power. In order toaddress this trade-off, PHR reporting based on the changing pathlossthreshold may be configured. In NR, both periodic reporting and eventthreshold-based reporting can be baseline as PHR triggering events.

The pathloss (PL) at a UE is generally measured from the differencebetween RSRP measurements and base station signalled transmission powerinformation (that is transmission power of cell-specific referencesignals (CRS)). In legacy LTE which uses omni-directional transmissions,it can be assumed that the pathloss may change relatively smoothly.However, in beamforming-based transmissions, because of the narrowerbandwidth and directional nature of the beams, the measured pathloss maysuddenly fluctuate with more frequent blockage as well as serving beamchanges.

Blockage (NLOS—no line of sight) can be of greater significance in NRbeamforming-based transmissions than in legacy LTE omni-directionaltransmissions. The directional line of sight (LOS) component accountsfor a sizable percentage of the received power, and, thus, is a largepart of reliable beamforming-based transmissions. LOS obstruction byobjects such as buildings, brick and even human could lead to increasedsignal outages.

To handle blockage in beamforming-based transmissions, the network cantrigger serving beam changes to change the serving beam based on the UEfeedback of measured beam quality. A serving beam change may involve asudden drop or rise in the received reference signal receive power(RSRP), reflecting the changes in pathloss and beamforming gain. Theserving beam change may be based on a beam measurement event configuredby a base station or on a beam measurement report from the UE. For thebeam measurement event, the quality of another beam may become betterthan the serving beam by at least a threshold amount. The UE may changethe serving beam when the RSRP of the target beam is higher than theserving beam. In the beam measurement report method, the base stationdecides the serving beam based on the measurement report and identifiesthe change of the serving beam to the UE. Before the beam change occursto the target beam, the UE estimates the pathloss of the previous beam,while after the beam change, the UE will measure pathloss on the newserving beam.

In NR mmWave deployments, special issues may arise when applying legacypower control procedures. For example, beam quality may fluctuate morequickly, which may add uncertainty to the knowledge of available powerat the UE side. Thus, during power adjustment, the serving beam pair maybe changed quickly due to beam blockage. The current standards suggest abeam-specific power control, even though the legacy systems provide aUE-based power control. Such suggested beam-specific power controldefines the possibility for beam-specific open and closed loopparameters. A given base station may be aware of the power headroomdifferences for different waveforms, if the UE can be configured forboth waveforms.

In legacy LTE, measured pathloss (PL) is determined according to thefollowing equation:PL=ReferenceSignalPower−L3 filtered RSRP  (2)Where the layer 3 filtered RSRP is based on CRS and ReferenceSignalPoweris provided by higher layers via system information broadcasts (e.g.,SIB2). Several special issues may arise in NR deployments. For example,NR deployments may not typically transmit L3 CRS at a rate that would befrequent enough to provide RSRP quickly enough to address the fast beamchanges. The more frequent reference signals in NR deployments includeNR synchronization signals (NR-SS) and channel state information (CSI)reference signals (CSI-RS). NR-SS have been suggested for 5G NR networksas synchronization signals similar to the PSS/SSS/PBCH of LTE networks.As currently considered, NR-SS may be an always-on periodic signal.Thus, pathloss measurement in N, deployments could rely on either NR-SSor CSI-RS for performing the beam-specific RSRP measurements, instead ofCRS. NR-SS and CSI-RS may have different beamforming gain, and CSI-RSmay not even always be on. Therefore, in beam-specific power controloperations, the issue arises over the use of L3 filtered beam RSRP vs.L1 filtered beam quality.

Additionally, in NR deployments, downlink beamforming gain may belargely different from uplink beamforming gain. This could occur becausedownlink and uplink transmissions may use different antenna panels.Moreover, different beam patterns may be used to adapt differentinterference environments for downlink and uplink transmissions, as wellas circumstances in which the downlink associated base station may bedifferent from the uplink associated base station (which may also be anissue in some LTE networks).

As noted above, legacy PHR reporting in LTE is generally UE-specific.However, the standards for NR network deployments has suggested thatbeam-specific power control be used. For example, during poweradjustment, the beam pair may be changed (beam change) due to beamblockage. A UE-specific approach may not result in accurate operations,because a base station may not be certain which beam's PHR the UE isreporting when beam changing occurs. It has further been observed that,in beamforming deployments, such as NR mmWave operations, a beam energychange of up to 15 dB may be experienced between the best beam and thenext best beam of the set of serving beams. Thus, relying on the PHR ofthe wrong beam in scheduling and link adaptation may result in adiminished communications experience. Moreover, considering such a largedifference in beam energy, PHR reporting and event triggering becomecoupled issues, as the PHR event trigger in legacy LTE systems is alsonot beam-specific. Accordingly, various aspects of the presentdisclosure are directed to power control procedures having beam-specificperiodic PHR reporting plus UE-specific event threshold PHR reporting.

FIG. 4 is a block diagram illustrating example blocks executed toimplement one aspect of the present disclosure. The example blocks willalso be described with respect to UE 115 as illustrated in FIG. 9. FIG.9 is a block diagram illustrating UE 115 configured according to oneaspect of the present disclosure. UE 115 includes the structure,hardware, and components as illustrated for UE 115 of FIG. 2. Forexample, UE 115 includes controller/processor 280, which operates toexecute logic or computer instructions stored in memory 282, as well ascontrolling the components of UE 115 that provide the features andfunctionality of UE 115. UE 115, under control of controller/processor280, transmits and receives signals via wireless radios 900 a-r andantennas 252 a-r. Wireless radios 900 a-r includes various componentsand hardware, as illustrated in FIG. 2 for eNB 105, includingmodulator/demodulators 254 a-r, MIMO detector 256, receive processor258, transmit processor 264, and TX MIMO processor 266.

At block 400, a UE determines a beam-specific periodic PHR in responseto expiration of a first reporting timer. For example, UE 115, undercontrol of controller/processor 280, executes periodic timer 903, storedin memory 282. Periodic timer 903 counts between times when UE 115 willsend a beam-specific PHR to the serving base station. On expiration ofperiodic timer 903, UE 115 executes power headroom logic 901, stored inmemory 282. The execution environment of power headroom logic measuresthe power headroom associated with the currently serving one or morebeams. UE 115 then executes PHR generator 902 to generate the periodicPHR. At block 401, the UE transmits the beam-specific PHR to the servingbase station. With the periodic reporting, when the periodic timerexpires, UE 115 would report a beam-specific periodic PHR via wirelessradios 900 a-r and antennas 252 a-r. This may be accomplished in anumber of ways. For example, UE 115 may determine the power headroom foreach of the serving beams and transmit the aggregate PHR that includesthe power headroom for all of the beams. Alternatively, UE 115 may bescheduled by the base station to measure and report the PHR for each ofthe serving beams in different slots or at different times.

At block 402, the UE detects a report trigger event. UE 115, undercontrol controller/processor 280, accesses event triggers 905, stored inmemory 282. UE 115 may determine what events will trigger theevent-trigger PHR. The report trigger event may include detecting thechange in pathloss of the current serving beam by a predeterminedamount. For example, UE 115 would execute measurement logic 906, storedin memory 282, to measure and maintain the pathloss of the serving beam.Additionally, a report trigger event may be defined for beam changes.Thus, UE would execute beam change logic 907, stored in memory 282, tokeep track of any beam changes that may occur at UE 115. At block 403,the UE determines a UE-specific trigger PHR in response to the reporttriggering event and expiration of a second timer, and, at block 404,transmits the UE-specific trigger PHR to the serving base station. If apathloss change is detected using measurement logic 906, beyond thatpredetermined amount, as may be stored at event triggers 905, or a beamchange occurs, as tracked by the execution environment of beam changelogic 907, UE 115 accesses threshold reporting timer 904, stored inmemory 282, to determine whether threshold reporting timer 904 hasexpired. If both the event is detected and threshold reporting timer 904have expired, UE 115 will determine a UE-specific PHR by executing PHRgenerator 902. The UE-specific PHR could be either for only the currentserving beam or could be for all of the serving beams. UE 115 will thentransmit the UE-specific PHR via wireless radios 900 a-r and antennas252 a-r.

FIG. 5 is a block diagram illustrating a base station 105 communicatingwith UE 115 using mmWave beamforming, in which base station 105 and UE115 are configured according to aspects of the present disclosure. UE115 is in motion within coverage area 500 of base station 105. Inserving UE 115, base station 105 beam forms a set of serving beams 501.While each serving beams 501 is a serving beam, there may be only one ofserving beams 501-a-501-d actually serving UE 115 at a given time. As UE115 moves across coverage area 500, the quality of the current servingbeam may change or the current serving beam may be blocked, causing UE115 to beam change to the best of the set of serving beams 501. Asnoted, the because of the beamforming by base station 105, there may bea beam energy change of up to 15 dB between the best beam and the nextbest beam of the set of serving beams 501. In one example of operation,after expiration of the periodic PHR timer, UE 115 may determine powerheadroom and transmit a PHR to base station 105.

In one possible scenario, UE 115 may reuse the legacy LTE PHR reportingby reporting only one periodic PHR for current serving beam. Forexample, if, at the expiration of the periodic PHR timer, UE 115 iscurrently served by serving beam 501-b, UE 115 will calculate the powerheadroom of serving beam 501-b and transmit it in a PHR to base station105. Base station 105 estimate the other beams' PHR based on anestimation for beamforming gain difference in UE 115, based on the samenominal UE maximum transmit power (P_(MAX)). However, in such a possiblescenario, the serving beam may change over the periodic PHR timer.Therefore, base station 105 may not have a timely PHR for thealternative beams.

FIG. 6A is a block diagram illustrating base station 105 and UE 115configured according to one aspect of the present disclosure. When UE115 transmits the periodic PHR to base station 105 (FIG. 5), it maytransmit one periodic PHR that includes the power headroom informationof all serving beams. A typical PHR is formatted as an octet, with a6-bit power headroom and two reserved bit. When transmitting oneperiodic PHR that includes power headroom information for all of theserving beams, an aggregated PHR 600 is generated. UE 115 aggregates the6-bit power headroom information 601 for beam #1 with the 6-bit powerheadroom information 602 for beam #2 into aggregated PHR. 600. The tworeserved bits may further be used by UE 115 to identify which of thebeams the PHR goes with, Thus. beam index 603 identifies beam #1 whilebeam index 604 identifies beam #2. Base station 105 would then be ableto identify which beam the PHR information belongs to.

FIG. 6B is a block diagram illustrating base station 105 and UE 115configured according to another aspect of the present disclosure. PHRreporting according to the aspect illustrated in FIG. 6B reuses thelegacy LTE. However, base station 105 configures UE 115 to measure andreport PHR at different a period and/or at an offset for the differentbeams of the set of serving beams. UE 115 is configured to report PHR605, including the power headroom information 607 for beam #1, at slot1, and is configured to report PHR 606, including power headroominformation 608 for beam #2, at slot N. Therefore, over the course oftransmissions by UE 115, base station 105 will receive the PHR for eachof the beams in the set of serving beams.

It should be noted that, such aspects may only work for periodicreference signals, such as CSI-RS and NR-SS. Moreover, a new periodicalPHR trigger may be configured for a set of beams, where eachconfiguration includes both a period and/or an offset for determiningand reporting the PHR for each serving beam in different reports orslots.

Referring back to FIG. 5, an additional aspect that may be illustratedby FIG. 5 include PHR reporting based on an event trigger. For example,an event trigger may be the change in pathloss of a serving beam thatexceeds a predetermined threshold. In the presently described example,the legacy LTE procedures are reused by UE 115 in reporting one PHR whenthe measured pathloss of the current serving beam exceeds thepredetermined threshold and expiration of a threshold reporting timer.As noted, the threshold reporting timer prevents UE 115 from reportingPHR to frequently when UE 115 is experiencing rapid changes in pathloss.Thus, when UE 115 calculates a change in pathloss of the current servingbeam, beam 501-a, that exceeds the threshold level, UE 115 checksthreshold reporting timer to determine if the timer has expired. If thetimer has expired, UE 115 will calculate the power headroom and generatethe PHR to report to base station 105. Otherwise, if the thresholdreporting timer has not expired, UE 115 will not generate a PHR, but,instead, continue operations. If, when the threshold reporting timerdoes expire, and the measured pathloss change at the expiration stillexceeds the threshold level, UE 115 will generate and transmit a PHR forbase station 105.

In the currently-described example aspect, the pathloss threshold andthreshold reporting timer may apply across the set of serving beams 501.Thus, in the presently-described aspect, the pathloss threshold andthreshold reporting timer will be common to UE 115 for all servingbeams. For example, if UE 115 experiences an NLOS blockage of servingbeam 501-a and determines to beam change to serving beam 501-b,threshold reporting timer will continue without reset, in addition tothe same pathloss threshold and any other protocol variable being thesame for serving beam 501-b.

With event-trigger PHR procedures, UE 115 may report a single PHR tobase station 105, as in the legacy LTE procedures. The single PHRimplies that the event-triggered PHR calculated and transmitted by UE115 to base station 105 does not distinguish beams. The beam-specificPHRs would, instead, be reported by UE 115 during the periodic PHRreporting. Two sub-solutions for PHR reporting. Alt-1-a: report just onePHR (same as LTE). It implies that prohibit PHR does not distinguishbeams (assuming that beam-specific PHR is reported in periodical PHR).

In an alternative of the presently-described aspect, UE 115 may report asingle PHR to base station 105 that includes the power headroominformation for all of the serving beams. For example, referring back toFIG. 6A, in the presently-described aspect, aggregated PHR 600corresponds to the event-trigger PHR, with the power headroominformation 601 for beam #1 and the power headroom information 602 forbeam #2. Similar to the periodic PHR procedure described previously forFIG. 6A, event-trigger version of aggregated PHR 600 includes beamindices 603 and 604 in the reserved 2-bit location of the PHR octet thatidentifies to base station 105 which beam power headroom information 601and 602 applies to.

As noted, the legacy LTE event-trigger PHR reporting procedures includepathloss change threshold values ranging from 1, 3, and 6 dB. However,aspects of the present disclosure operated in 5G mmWave deployments maynot properly trigger based on the pathloss changes that may be observedwith mmWave beamforming (e.g., approximately 15 dB). In order toaccommodate the larger potential pathloss change in mmWave beamformingdeployments, aspects of the present disclosure may change the legacypathloss threshold to at least 15 dB. Thus, referring back to FIG. 5, ifUE 115 detects a pathloss on serving beam 501-a that meets the 15 dBpathloss threshold, UE 115 will trigger calculation and transmission ofan event-trigger PHR for base station 105.

Additional aspects of the present disclosure may add new trigger eventsto the event-trigger PHR reporting procedures. In one such example,serving beam change may be identified as an event trigger for UE 115.Referring again to FIG. 5, in the presently-described additional aspect,UE 115 experiences NLOS blockage of current serving beam 501-a andselects to beam change to beam 501-b. Upon selecting to beam change, UE115 checks the threshold reporting timer to determine if it has expired.If so, then UE 115 will calculate the power headroom on beam 501-b andgenerate a event-trigger PHR for base station 105 with the powerheadroom information.

FIG. 6C is a block diagram illustrating base station 105 and UE 115configured according to another aspect of the present disclosure. WhenUE 115 selects the beam change to serving beam 501-b (FIG. 5), itcalculates power headroom information 610 for serving beam 501-b andincludes it in event-trigger PHR 609. In order to inform base station105 which beam power headroom information 610 corresponds to, the 2-bitreserve of the PHR octet may include beam index 611, which identifiesserving beam 501-b. Because the beam change is configured as an eventtrigger, the threshold reporting timer and protocol variables should bereset when such an event is detected. Thus, the timers and protocolvariables of the presently-described example aspect are maintained perbeam and not per UE.

It should be noted that, in the presently described example, thepathloss threshold value may not need to be extended to the higherpotential pathloss change that may be experienced in mmWave beamforming.Such high levels of potential pathloss are generally associated with thedifferent beams of the set of serving beams. Thus, when beam change isalready an event trigger, the pathloss threshold value may not need toreflect the larger value for mmWave beamforming in such aspects basestation 105 and UE 115 would have no ambiguity on the serving beam, asthe beam switch is robust.

It should be noted that additional or alternative aspect may provide forbeam-specific event-trigger PHR from UE 115, where base station 105configures UE 115 to monitor multiple serving beam's PHRs in differentslots. In such aspects, base station 105 would receive event-trigger PHRfor additional serving beams in the different configured slots. Thismultiple serving beam PHR procedure may work efficiently using periodicCSI-RS or NR-SS. Such aspects would include new event-trigger PHRconfigurations for a set of beams, where each includes different periodsand/or offsets. Separate timers and protocol variables may be maintainedper beam, without necessity to extend the pathloss threshold range tothe higher levels observed in mmWave beamforming.

The various aspects of the present disclosure provide for power controlprocesses for mmWave beamforming deployments including both periodic PHRreporting and event-trigger PHR reporting. Pathloss estimation isperformed for determining certain trigger events. However, as indicatedpreviously, the nature of mmWave beamforming potentially creates issuesin extending the legacy LTE PHR reporting procedures, as theomni-directional CRS may not be adequate to efficiently measure orestimate pathloss in rapidly changing directional beams.

Additional aspects of the present disclosure may provide for referencesignals that may address the issues in mmWave beams. In one exampleimplementation, CSI-RS are configured as the baseline reference signalfor pathloss estimation in mmWave beamforming. CSI-RS may provide moreaccurate pathloss estimates because the UE would be in a connected-modeand, thus, calculations on the CSI-RS would include downlink beamforminggain in the pathloss estimation.

Further aspects of the present disclosure may additionally provide forNR-SS as the reference signal for pathloss estimation. If NR-SS may beused in addition to CSI-RS, a serving base station may indicate which ofthese reference signals should be used for pathloss estimation throughdedicated signaling.

FIG. 7 is a block diagram illustrating example blocks executed toimplement one aspect of the present disclosure. The example blocks willalso be described with respect to the detail of UE 115 in FIG. 9. Atblock 700, a UE receives an identification signal from a serving basestation that identifies one or more reference signals for pathlossmeasurement. The identification signal received by UE 115 may beincluded in power control configuration information received viaantennas 252 a-r and wireless radios 900 a-r and identify to UE 115whether CSI-RS or NR-SS are to be used for pathloss estimation. Suchpower control configuration information may be signaled at leastsemi-statically (e.g., radio resource control (RRC) or media accesscontrol (MAC) control element (MAC-CE)). Due to potential largebeamforming gain difference between different beams, the identificationsignal may also indicate to the UE which subset of CSI-RS to measure forpathloss estimation.

It should be noted that the indicated CSI-RS may be periodic,semi-periodic, or aperiodic CSI-RS.

At block 701, the UE measures a pathloss on the one or more referencesignals identified by the identification signal. For example, UE 115executes measurement logic 906 to measure the pathloss of the identifiedreference signals (NR-SS, CSI-RS, or a designated subset of CSI-RS) TheUE, at block 702, compares the measured pathloss to a threshold. triggervalue. Under control of controller/processor 280, UE 115 compares themeasured pathloss against the threshold trigger value stored at eventtriggers 905. If the measured pathloss exceeds the threshold triggervalue, then, at block 703, activates power headroom reporting. Thus, ifthe measured pathloss exceeds the event trigger, UE 115 will executepower headroom logic 901 and PHR generator 902 to measure the powerheadroom and send the PHR to the serving base station. According to thepresently-described aspect, dedicated signaling is used by the basestation to signal UE 115 which reference signals to use for pathlossestimation in the mmWave beamforming deployment.

While dedicated signaling may be used to identify the appropriatereference signals for pathloss estimation, issues may arise based on amismatch between uplink and downlink beamforming gain. As indicatedabove, such a mismatch may occur because downlink and uplinktransmissions use different antenna panels. Different beam patterns mayalso be used to adapt different interference environments for downlinkand uplink transmissions, as well as scenarios in which the base stationassociated with downlink may be different from the base stationassociated uplink transmissions.

To address the mismatch, in one example aspect, the UE may reuse thelegacy LTE pathloss estimation, in which the beam mismatch may becompensated for by the base station through implementation. While thecompensation may improve the mismatch, it may be difficult for the basestation to estimate UE receive beamforming gain if UE receiverbeamforming applies.

In an additional aspect of the present disclosure, in order to addressthe mismatch issue, a beam-specific pathloss offset may be added to thededicated signaling from the base station to the UE. Beam-specificpathloss offset corresponds to the downlink beamforming gain minus theuplink beamforming gain. If UE receiver beamforming is applied, the UEcould add offset attributable to UE receive beamforming gain.

It should be noted that, in order to address the mismatch between uplinkand downlink beamforming gain, a UE may reuse the legacy LTE pathlossestimation with the UE compensating for the beam mismatch throughimplementation. While no specification changes would be required in suchan option, it may be difficult for a UE to estimate the difference inbeamforming gain between uplink and downlink without more detailedsignaling exchanges with the serving base station.

FIG. 8 is a block diagram illustrating example blocks executed toimplement one aspect of the present disclosure. The example blocks willalso be described with respect to the detail of UE 115 in FIG. 9. Atblock 800, a UE determines a time period since a last beam change of oneor more serving beams received at the UE from a serving base station.For example, UE 115 executes beam change logic 907 to determine the timeperiod since the last beam change. At block 801, the UE measures apathloss of a beam-specific layer 3 reference signal on a currentserving beam in response to the time period exceeding a minimum timethreshold. When beam changes do not occur too frequently, use ofbeam-specific layer 3 reference signals for pathloss estimation by UE115 may be sufficient. UE 115, under control of controller/processor280, would execute measurement logic 906 to determine the pathlossestimation. At block 802 the UE measures the pathloss of a beam-specificlayer 1 reference signal on the current serving beam in response to thetime period being below the minimum time threshold. When beam changingoccurs more rapidly, the layer 3 signaling may not occur often enough tosufficiently provide UE 115 the signal for pathloss estimation. Thelayer 1 signaling would be preferable in order to address the morefrequent and beam-specific aspects of mmWave transmissions.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

The present disclosure comprises a first aspect, such as anon-transitory computer-readable medium having program code recordedthereon, the program code comprising:

program code executable by a computer for causing the computer todetermine, by a user equipment (UE), a beam-specific periodic powerheadroom report (PHR) in response to expiration of a first reportingtimer, wherein the UE receives communications from a serving basestation over one or more serving beams beamformed by the serving basestation;

program code executable by the computer for causing the computer totransmit, by the UE, the beam-specific periodic PHR to the serving basestation;

program code executable by the computer for causing the computer todetect, by the UE, a report triggering event;

program code executable by the computer for causing the computer todetermine, by the UE, a UE-specific trigger PHR in response to thereport triggering event and expiration of a second reporting timer;

program code executable by the computer for causing the computer totransmit, by the UE, the UE-specific trigger PHR to the serving basestation.

Based on the first aspect, the non-transitory computer-readable mediumof a second aspect,

wherein the program code executable by the computer for causing thecomputer to determine the beam-specific periodic PHR includes:

-   -   program code executable by the computer for causing the computer        to measure a power headroom for each beam of the one or more        serving beams; and    -   program code executable by the computer for causing the computer        to generate an aggregate PHR including the power headroom for        the each beam;

wherein the program code executable by the computer for causing thecomputer to transmit the beam-specific periodic PHR includes programcode executable by the computer for causing the computer to transmit theaggregate PHR.

Based on the second aspect, the non-transitory computer-readable mediumof a third aspect, wherein the program code executable by the computerfor causing the computer to generate further includes:

program code executable by the computer for causing the computer to adda beam identifier to the aggregate PHR, wherein the beam identifierindicates an associated beam of the one or more serving beamscorresponding to the power headroom of the aggregate PHR.

Based on the first aspect, the non-transitory computer-readable mediumof a fourth aspect, further including:

program code executable by the computer for causing the computer toreceive, at the UE, beam reporting configuration from the serving basestation, wherein the beam reporting configuration configures the UE toreport the beam-specific periodic PHR for each of the one or moreserving beams at a different reporting occasion,

-   -   wherein the program code executable by the computer for causing        the computer to determine the beam-specific periodic PHR        includes program code executable by the computer for causing the        computer to determine the beam-specific periodic PHR of a        currently-scheduled beam of the one or more serving beams, and    -   wherein the program code executable by the computer for causing        the computer to transmit the beam-specific periodic PHR includes        program code executable by the computer for causing the computer        to transmit the beam-specific periodic PHR of the        currently-scheduled beam at a currently-scheduled reporting        occasion.

Based on the fourth aspect, the non-transitory computer-readable mediumof a fifth aspect, wherein the beam reporting configuration includes oneof:

a different period of the first reporting timer for each of the one ormore serving beams; or

a different offset to the first reporting tinier for each of the one ormore serving beams.

Based on the first aspect, the non-transitory computer-readable mediumof a sixth aspect,

wherein the program code executable by the computer for causing thecomputer to determine the UE-specific trigger PHR includes program codeexecutable by the computer for causing the computer to measure a powerheadroom for a current serving beam of the one or more serving beams,

wherein the UE-specific trigger PHR includes the power headroom for thecurrent serving beam.

Based on the first aspect, the non-transitory computer-readable mediumof a seventh aspect,

wherein the program code executable by the computer for causing thecomputer to determine the UE-specific trigger PHR includes:

-   -   program code executable by the computer for causing the computer        to measure a power headroom for each beam of the one or more        serving beams; and    -   program code executable by the computer for causing the computer        to generate an aggregate trigger PHR including the power        headroom for the each beam;

wherein the program code executable by the computer for causing thecomputer to transmit the UE-specific trigger PHR includes program codeexecutable by the computer for causing the computer to transmit theaggregate trigger PHR.

Based on the first aspect, the non-transitory computer-readable mediumof an eighth aspect, wherein the second reporting tinier and thresholdtrigger value of the report triggering event are common to the UE andshared across the one or more serving beams, such that a serving beamchange does not trigger restart of the second reporting timer.

Based on the first aspect, the non-transitory computer-readable mediumof a ninth aspect, wherein the report triggering event includes one ormore of:

a pathloss measured on a current serving beam of the one or more servingbeams; and

a serving beam change at the UE.

Based on the ninth aspect, the non-transitory computer-readable mediumof a tenth aspect, further including:

program code executable by the computer for causing the computer toreset the second reporting timer in response to the serving beam changeat the UE.

Based on the first aspect, the non-transitory computer-readable mediumof an eleventh aspect, wherein the report triggering event includes apathloss measured on a current serving beam of the one or more servingbeams, wherein a threshold trigger value of the pathloss is at least 15dB.

A twelfth aspect of the non-transitory computer-readable medium of anycombination of the first through eleventh aspects.

The present disclosure comprises a thirteenth aspect, such as anon-transitory computer-readable medium having program code recordedthereon, the program code comprising:

program code executable by a computer for causing the computer toreceive, at a user equipment (UE), an identification signal from aserving base station, wherein the identification signal identifies oneor more reference signals for pathloss measurement;

program code executable by the computer for causing the computer tomeasure, by the UE, a pathloss on the one or more reference signalsidentified by the identification signal;

program code executable by the computer for causing the computer tocompare, by the UE, the pathloss to a threshold trigger value; and

program code executable by the computer for causing the computer toactivate, by the UE, power headroom reporting in response to thepathloss exceeding the threshold trigger value.

Based on the thirteenth aspect, the non-transitory computer-readablemedium of a fourteenth aspect, wherein the one or more reference signalsidentified by the identification signal includes one of:

new radio (NR) synchronization signals (NR-SS); or

channel state information (CSI) reference signals (CSI-RS).

Based on the thirteenth aspect, the non-transitory computer-readablemedium of a fifteenth aspect, wherein the one or more reference signalsidentified by the identification signal includes a subset of channelstate information (CSI) reference signals (CSI-RS).

Based on the fifteenth aspect, the non-transitory computer-readablemedium of a. sixteenth aspect, wherein each of the CSI-RS of the subsetincludes one of:

a beamforming gain above a threshold gain value;

a downlink beamforming gain within a predetermined range of an uplinkbeamforming gain.

Based on the thirteenth aspect, the non-transitory computer-readablemedium of a seventeenth aspect, wherein the identification signalfurther includes a pathloss offset, wherein the pathloss offsetcorresponds to a downlink beamforming gain minus an uplink beamforminggain.

Based on the seventeenth aspect, the non-transitory computer-readablemedium of an eighteenth aspect, wherein the pathloss offset correspondsto a sum of the downlink beamforming gain and a UE receive beamforminggain minus the uplink beamforming gain.

A nineteenth aspect of the non-transitory computer-readable medium ofany combination of the thirteenth through eighteenth aspects

The present disclosure comprises a twentieth aspect, such as anon-transitory computer-readable medium having program code recordedthereon, the program code comprising:

program code executable by a computer for causing the computer todetermine, by a user equipment (UE), a time period since a last beamchange of one or more serving beams received at the UE from a servingbase station;

program code executable by the computer for causing the computer tomeasure, by the UE, a pathloss of a beam-specific layer 3 referencesignal on a current serving beam in response to the time periodexceeding a minimum time threshold; and

program code executable by the computer for causing the computer tomeasure, by the UE, the pathloss of a beam-specific layer 1 referencesignal on the current serving beam in response to the time period beingbelow the minimum time threshold.

The present disclosure comprises a twenty-first aspect, such as anapparatus configured for wireless communication, the apparatuscomprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured:

-   -   to determine, by a user equipment (UE), a beam-specific periodic        power headroom report (PHR) in response to expiration of a first        reporting timer, wherein the UE receives communications from a        serving base station over one or more serving beams beamformed        by the serving base station;    -   to transmit, by the UE, the beam-specific periodic PHR to the        serving base station;    -   to detect, by the UE, a report triggering event;    -   to determine, by the UE, a UE-specific trigger PHR in response        to the report triggering event and expiration of a second        reporting timer;    -   to transmit, by the UE, the UE-specific trigger PHR to the        serving base station.

Based on the twenty-first aspect, the apparatus of a twenty-second,

wherein the configuration of the at least one processor to determine thebeam-specific periodic PHR includes configuration of the at least oneprocessor:

-   -   to measure a power headroom for each beam of the one or more        serving beams; and    -   to generate an aggregate PHR including the power headroom for        the each beam;

wherein the configuration of the at least one processor to transmit thebeam-specific periodic PHR includes configuration to transmit theaggregate PHR.

Based on the twenty-second aspect, the apparatus of a twenty-third,wherein the configuration of the at least one processor to generatefurther includes configuration to add a beam identifier to the aggregatePHR, wherein the beam identifier indicates an associated beam of the oneor more serving beams corresponding to the power headroom of theaggregate PHR.

Based on the twenty-first aspect, the apparatus of a twenty-fourth,further including configuration of the at least one processor toreceive, at the UE, beam reporting configuration from the serving basestation, wherein the beam reporting configuration configures the toreport the beam-specific periodic PHR for each of the one or moreserving beams at a different reporting occasion,

-   -   wherein the configuration of the at least one processor to        determine the beam-specific periodic PHR includes configuration        to determine the beam-specific periodic PHR of a        currently-scheduled beam of the one or more serving beams, and    -   wherein the configuration of the at least one processor to        transmit the beam-specific periodic PHR includes configuration        to transmit the beam-specific periodic PHR of the        currently-scheduled beam at a currently-scheduled reporting        occasion.

Based on the twenty-fourth aspect, the apparatus of a twenty-fifth,wherein the beam reporting configuration includes one of:

a different period of the first reporting tinier for each of the one ormore serving beams; or

a different offset to the first reporting timer for each of the one ormore serving beams.

Based on the twenty-first aspect, the apparatus of a twenty-sixth,

wherein the configuration of the at least one processor to determine theUE-specific trigger PHR includes configuration to measure a powerheadroom for a current serving beam of the one or more serving beams,

wherein the UE-specific trigger PHR includes the power headroom for thecurrent serving beam.

Based on the twenty-first aspect, the apparatus of a twenty-seventh

wherein the configuration of the at least one processor to determine theUE-specific trigger PHR includes configuration of the at least oneprocessor:

-   -   to measure a power headroom for each beam of the one or more        serving beams; and    -   to generate an aggregate trigger PHR including the power        headroom for the each beam;

wherein the configuration of the at least one processor to transmit theUE-specific trigger PHR includes configuration to transmit the aggregatetrigger PHR.

Based on the twenty-first aspect, the apparatus of a twenty-eighth,wherein the second reporting timer and threshold trigger value of thereport triggering event are common to the UE and shared across the oneor more serving beams, such that a serving beam change does not triggerrestart of the second reporting timer.

Based on the twenty-first aspect, the apparatus of a twenty-ninth,wherein the report triggering event includes one or more of:

a pathloss measured on a current serving beam of the one or more servingbeams; and

a serving beam change at the UE.

Based on the twenty-ninth aspect, the apparatus of a thirtieth aspect,further including configuration of the at least one processor to resetthe second reporting timer in response to the serving beam change at theUE.

Based on the twenty-first aspect, the apparatus of a thirty-firstaspect, wherein the report triggering event includes a pathloss measuredon a current serving beam of the one or more serving beams, wherein athreshold trigger value of the pathloss is at least 15 dB.

A thirty-second aspect of the non-transitory computer-readable medium ofany combination of the twenty-first through thirty-first aspects

The present disclosure comprises a thirty-third aspect, such as anapparatus configured for wireless communication, the apparatuscomprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured:

-   -   to receive, at a user equipment (UE), an identification signal        from a serving base station, wherein the identification signal        identifies one or more reference signals for pathloss        measurement;    -   to measure, by the UE, a pathloss on the one or more reference        signals identified by the identification signal;    -   to compare, by the UE, the pathloss to a threshold trigger        value; and    -   to activate, by the UE, power headroom reporting in response to        the pathloss exceeding the threshold trigger value.

Based on the thirty-third aspect, the apparatus of a thirty-fourthaspect, wherein the one or more reference signals identified by theidentification signal includes one of:

new radio (NR) synchronization signals (NR-SS); or

channel state information (CSI) reference signals (CSI-RS).

Based on the thirty-third aspect, the apparatus of a thirty-fifthaspect, wherein the one or more reference signals identified by theidentification signal includes a subset of channel state information(CSI) reference signals (CSI-RS).

Based on the thirty-fifth aspect, the apparatus of a thirty-sixthaspect, wherein each of the CSI-RS of the subset includes one of:

a beamforming gain above a threshold gain value;

a downlink beamforming gain within a predetermined range of an uplinkbeamforming gain.

Based on the thirty-third aspect, the apparatus of a thirty-seventhaspect, wherein the identification signal further includes a pathlossoffset, wherein the pathloss offset corresponds to a downlinkbeamforming gain minus an uplink beamforming gain.

Based on the thirty-seventh aspect, the apparatus of a thirty-eighthaspect, wherein the pathloss offset corresponds to a sum of the downlinkbeamforming gain and a UE receive beamforming gain minus the uplinkbeamforming gain.

A thirty-ninth aspect of the non-transitory computer-readable medium ofany combination of the thirty-third through thirty-eighth aspects

The present disclosure comprises a fortieth aspect, such as an apparatusconfigured for wireless communication, the apparatus comprising:

at least one processor; and

a memory coupled to the at least one processor,

wherein the at least one processor is configured:

-   -   to determine, by a user equipment (UE), a time period since a        last beam change of one or more serving beams received at the UE        from a serving base station;    -   to measure, by the UE, a pathloss of a beam-specific layer 3        reference signal on a current serving beam in response to the        time period exceeding a minimum time threshold; and    -   to measure, by the UE, the pathloss of a beam-specific layer 1        reference signal on the current serving beam in response to the        time period being below the minimum time threshold.

The functional blocks and modules in FIGS. 4, 7, and 8 may compriseprocessors, electronics devices, hardware devices, electronicscomponents, logical circuits, memories, software codes, firmware codes,etc., or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure. Skilled artisans will also readilyrecognize that the order or combination of components, methods, orinteractions that are described herein are merely examples and that thecomponents, methods, or interactions of the various aspects of thepresent disclosure may be combined or performed in ways other than thoseillustrated and described herein.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another.Computer-readable storage media may be any available media that can beaccessed by a general purpose or special purpose computer. By way ofexample, and not limitation, such computer-readable media can compriseRAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic diskstorage or other magnetic storage devices, or any other medium that canbe used to carry or store desired program code means in the form ofinstructions or data structures and that can be accessed by ageneral-purpose or special-purpose computer, or a general-purpose orspecial-purpose processor. Also, a connection may be properly termed acomputer-readable medium. For example, if the software is transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, or digital subscriber line (DSL), thenthe coaxial cable, fiber optic cable, twisted pair, or DSL, are includedin the definition of medium. Disk and disc, as used herein, includescompact disc (CD), laser disc, optical disc, digital versatile disc(DVD), floppy disk and blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

As used herein, including in the claims, the term “and/or,” when used ina list of two or more items, means that any one of the listed items canbe employed by itself, or any combination of two or more of the listeditems can be employed. For example, if a composition is described ascontaining components A, B, and/or C, the composition can contain Aalone; B alone; C alone; A and B in combination; A and C in combination;B and C in combination; or A, B, and C in combination. Also, as usedherein, including in the claims, “or” as used in a list of itemsprefaced by “at least one of” indicates a disjunctive list such that,for example, a list of “at least one of A, B, or C” means A or B or C orAB or AC or BC or ABC (i.e., A and B and C) or any of these in anycombination thereof.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method of wireless communication, comprising:determining, by a user equipment (UE), a beam-specific periodic powerheadroom report (PHR) in response to expiration of a first reportingtimer, wherein the UE receives communications from a serving basestation over one or more serving beams beamformed by the serving basestation; transmitting, by the UE, the beam-specific periodic PHR to theserving base station; detecting, by the UE, a report triggering event,wherein the report triggering event includes one or more of: a pathlossmeasured on a current serving beam of the one or more serving beams; anda serving beam change at the UE; determining, by the UE, a UE-specifictrigger PHR in response to the report triggering event and expiration ofa second reporting timer; and transmitting, by the UE, the UE-specifictrigger PHR to the serving base station.
 2. The method of claim 1,wherein the determining the beam-specific periodic PHR includes:measuring a power headroom for each beam of the one or more servingbeams; and generating an aggregate PHR including the power headroom forthe each beam; wherein the transmitting the beam-specific periodic PHRincludes transmitting the aggregate PHR.
 3. The method of claim 2,wherein the generating further includes: adding a beam identifier to theaggregate PHR, wherein the beam identifier indicates an associated beamof the one or more serving beams corresponding to the power headroom ofthe aggregate PHR.
 4. The method of claim 1, further including:receiving, at the UE, beam reporting configuration from the serving basestation, wherein the beam reporting configuration configures the UE toreport the beam-specific periodic PHR for each of the one or moreserving beams at a different reporting occasion, wherein the determiningthe beam-specific periodic PHR includes determining the beam-specificperiodic PHR of a currently-scheduled beam of the one or more servingbeams, and wherein the transmitting the beam-specific periodic PHRincludes transmitting the beam-specific periodic PHR of thecurrently-scheduled beam at a currently-scheduled reporting occasion. 5.The method of claim 4, wherein the beam reporting configuration includesone of: a different period of the first reporting timer for each of theone or more serving beams; or a different offset to the first reportingtimer for each of the one or more serving beams.
 6. The method of claim1, wherein the determining the UE-specific trigger PHR includesmeasuring a power headroom for a current serving beam of the one or moreserving beams, wherein the UE-specific trigger PHR includes the powerheadroom for the current serving beam.
 7. The method of claim 1, whereinthe determining the UE-specific trigger PHR includes: measuring a powerheadroom for each beam of the one or more serving beams; and generatingan aggregate trigger PHR including the power headroom for the each beam;wherein the transmitting the UE-specific trigger PHR includestransmitting the aggregate trigger PHR.
 8. The method of claim 1,wherein the second reporting timer and threshold trigger value of thereport triggering event are common to the UE and shared across the oneor more serving beams, such that a serving beam change does not triggerrestart of the second reporting timer.
 9. The method of claim 1, furtherincluding: resetting the second reporting timer in response to theserving beam change at the UE.
 10. The method of claim 1, wherein thereport triggering event includes a pathloss measured on a currentserving beam of the one or more serving beams, wherein a thresholdtrigger value of the pathloss is at least 15 dB.
 11. A method ofwireless communication, comprising: determining, by a user equipment(UE), a time period since a last beam change of one or more servingbeams received at the UE from a serving base station; measuring, by theUE, a pathloss of a beam-specific layer 3 reference signal on a currentserving beam in response to the time period exceeding a minimum timethreshold; and measuring, by the UE, the pathloss of a beam-specificlayer 1 reference signal on the current serving beam in response to thetime period being below the minimum time threshold.
 12. An apparatusconfigured for wireless communication, comprising: means fordetermining, by a user equipment (UE), a beam-specific periodic powerheadroom report (PHR) in response to expiration of a first reportingtimer, wherein the UE receives communications from a serving basestation over one or more serving beams beamformed by the serving basestation; means for transmitting, by the UE, the beam-specific periodicPHR to the serving base station; means for detecting, by the UE, areport triggering event, wherein the report triggering event includesone or more of: a pathloss measured on a current serving beam of the oneor more serving beams; and a serving beam change at the UE; means fordetermining, by the UE, a UE-specific trigger PHR in response to thereport triggering event and expiration of a second reporting timer; andmeans for transmitting, by the UE, the UE-specific trigger PHR to theserving base station.
 13. The apparatus of claim 12, wherein the meansfor determining the beam-specific periodic PHR includes: means formeasuring a power headroom for each beam of the one or more servingbeams; and means for generating an aggregate PHR including the powerheadroom for the each beam; wherein the means for transmitting thebeam-specific periodic PHR includes means for transmitting the aggregatePHR.
 14. The apparatus of claim 13, wherein the means for generatingfurther includes: means for adding a beam identifier to the aggregatePHR, wherein the beam identifier indicates an associated beam of the oneor more serving beams corresponding to the power headroom of theaggregate PHR.
 15. The apparatus of claim 12, further including: meansfor receiving, at the UE, beam reporting configuration from the servingbase station, wherein the beam reporting configuration configures the UEto report the beam-specific periodic PHR for each of the one or moreserving beams at a different reporting occasion, wherein the means fordetermining the beam-specific periodic PHR includes means fordetermining the beam-specific periodic PHR of a currently-scheduled beamof the one or more serving beams, and wherein the means for transmittingthe beam-specific periodic PHR includes means for transmitting thebeam-specific periodic PHR of the currently-scheduled beam at acurrently-scheduled reporting occasion.
 16. The apparatus of claim 15,wherein the beam reporting configuration includes one of: a differentperiod of the first reporting timer for each of the one or more servingbeams; or a different offset to the first reporting timer for each ofthe one or more serving beams.
 17. The apparatus of claim 12, whereinthe means for determining the UE-specific trigger PHR includes means formeasuring a power headroom for a current serving beam of the one or moreserving beams, wherein the UE-specific trigger PHR includes the powerheadroom for the current serving beam.
 18. The apparatus of claim 12,wherein the means for determining the UE-specific trigger PHR includes:means for measuring a power headroom for each beam of the one or moreserving beams; and means for generating an aggregate trigger PHRincluding the power headroom for the each beam; wherein the means fortransmitting the UE-specific trigger PHR includes means for transmittingthe aggregate trigger PHR.
 19. The apparatus of claim 12, wherein thesecond reporting timer and threshold trigger value of the reporttriggering event are common to the UE and shared across the one or moreserving beams, such that a serving beam change does not trigger restartof the second reporting timer.
 20. The apparatus of claim 12, furtherincluding: means for resetting the second reporting timer in response tothe serving beam change at the UE.
 21. The apparatus of claim 12,wherein the report triggering event includes a pathloss measured on acurrent serving beam of the one or more serving beams, wherein athreshold trigger value of the pathloss is at least 15 dB.
 22. Anapparatus configured for wireless communication, comprising: means fordetermining, by a user equipment (UE), a time period since a last beamchange of one or more serving beams received at the UE from a servingbase station; means for measuring, by the UE, a pathloss of abeam-specific layer 3 reference signal on a current serving beam inresponse to the time period exceeding a minimum time threshold; andmeans for measuring, by the UE, the pathloss of a beam-specific layer 1reference signal on the current serving beam in response to the timeperiod being below the minimum time threshold.
 23. An apparatus forwireless communication, the apparatus comprising: at least oneprocessor; and a memory coupled to the at least one processor, whereinthe at least one processor is configured to perform operationsincluding: determining, by a user equipment (UE), a beam-specificperiodic power headroom report (PHR) in response to expiration of afirst reporting timer, wherein the UE receives communications from aserving base station over one or more serving beams beamformed by theserving base station; transmitting, by the UE, the beam-specificperiodic PHR to the serving base station; detecting, by the UE, a reporttriggering event, wherein the report triggering event includes one ormore of: a pathloss measured on a current serving beam of the one ormore serving beams; and a serving beam change at the UE; determining, bythe UE, a UE-specific trigger PHR in response to the report triggeringevent and expiration of a second reporting timer; and transmitting, bythe UE, the UE-specific trigger PHR to the serving base station.
 24. Theapparatus of claim 23, wherein the determining the beam-specificperiodic PHR includes: measuring a power headroom for each beam of theone or more serving beams; and generating an aggregate PHR including thepower headroom for the each beam; wherein the transmitting thebeam-specific periodic PHR includes transmitting the aggregate PHR. 25.The apparatus of claim 24, wherein the generating further includes:adding a beam identifier to the aggregate PHR, wherein the beamidentifier indicates an associated beam of the one or more serving beamscorresponding to the power headroom of the aggregate PHR.
 26. Theapparatus of claim 23, further including: receiving, at the UE, beamreporting configuration from the serving base station, wherein the beamreporting configuration configures the UE to report the beam-specificperiodic PHR for each of the one or more serving beams at a differentreporting occasion, wherein the determining the beam-specific periodicPHR includes determining the beam-specific periodic PHR of acurrently-scheduled beam of the one or more serving beams, and whereinthe transmitting the beam-specific periodic PHR includes transmittingthe beam-specific periodic PHR of the currently-scheduled beam at acurrently-scheduled reporting occasion.
 27. The apparatus of claim 26,wherein the beam reporting configuration includes one of: a differentperiod of the first reporting timer for each of the one or more servingbeams; or a different offset to the first reporting timer for each ofthe one or more serving beams.
 28. The apparatus of claim 23, whereinthe determining the UE-specific trigger PHR includes measuring a powerheadroom for a current serving beam of the one or more serving beams,wherein the UE-specific trigger PHR includes the power headroom for thecurrent serving beam.
 29. The apparatus of claim 23, wherein thedetermining the UE-specific trigger PHR includes: measuring a powerheadroom for each beam of the one or more serving beams; and generatingan aggregate trigger PHR including the power headroom for the each beam;wherein the transmitting the UE-specific trigger PHR includestransmitting the aggregate trigger PHR.
 30. The apparatus of claim 23,wherein the second reporting timer and threshold trigger value of thereport triggering event are common to the UE and shared across the oneor more serving beams, such that a serving beam change does not triggerrestart of the second reporting timer.
 31. The apparatus of claim 23,further including: resetting the second reporting timer in response tothe serving beam change at the UE.
 32. The apparatus of claim 23,wherein the report triggering event includes a pathloss measured on acurrent serving beam of the one or more serving beams, wherein athreshold trigger value of the pathloss is at least 15 dB.
 33. Anapparatus for wireless communication, the apparatus comprising: at leastone processor; and a memory coupled to the at least one processor,wherein the at least one processor is configured to perform operationsincluding: determining, by a user equipment (UE), a time period since alast beam change of one or more serving beams received at the UE from aserving base station; measuring, by the UE, a pathloss of abeam-specific layer 3 reference signal on a current serving beam inresponse to the time period exceeding a minimum time threshold; andmeasuring, by the UE, the pathloss of a beam-specific layer 1 referencesignal on the current serving beam in response to the time period beingbelow the minimum time threshold.